Method of making finned tubing



Sept .25,1928. v 1,685,270

H. W. BUNDY METHOD OF MAKING FINNED TUBING Filed July 14, 1927 2Sheets-Sheet 1 INVENTOR.

59272 if fiand q 'A TTORVEY.

Sept. 25, 1928.

v H. W. BUNDY METHOD OF MAKING FINNED TUBING.

Filed July 14, 1927 '2 Sheets-Sheet 2 INVEN-TOR. 1 20729 ATTORNEY. I

. Patented Sept. 25, 1928.

UNITED STATES PATENT "OFFICE.

mm? W. BUNDY, or nn rao nr, MICHIGAN.

T, amnion or MAKING. mma) TUBING.

.Applicatic'n filed m 14, 1927.- Serial No. aoam'.

This invention relates to 'a method of makby utilizing the rotarymovement of the tube, ing finned tubing and it has to do especially aseffected by the ro1ls2 and 3. v with a method wherein spiral fin isplaced Strip stock is drawn from a supply of upon a preformed tube. Istock 5 The method consists in the taking of a tube shown This stristock me be tinned reof any desired character and advancing the viouslyp flg to being put in the supply roll.

tube longitudinally while rotating the same. ever, it may not be tinnedin the supply roll"- referably inthe form of a'roll (not While the tubeis thus handled fin stock is spiand a coating of tin or solder may beapplied rally wrapped upon the tubeand secured as the stock is drawnfrom the supply. This thereto. The 'fin stock is treated in a novel isoptional,

manner and so that a relatively large contact step of tinning thestockafter it is drawn between the fin and the tube is efiected. The from thesupply. For this purpose the stock invention contemplates a methodwherein the is drawn through an acid bath, a solder bath, fin stock canbe wound upon the tube in such and then a cooling water bath inprogressive a manner as to reinforce the body of the tube steps, asshown in Fig. 1. I

thus permitting the use of a preformed tu The stock is then drawn over aroller 5, of relativelythin stock, or a tube which does which is merelya guide roller and turns the not have the strength required in thefinished stock through an angle of about 90. The finned tube, with thestock affording the stock is then drawn through a pair of rollersadditional strength requlred. 6 for the purpose'of bending the stock sothat In the accompanymgdrawmgs: it is angular in cross section. This isbest Fig. 1 is an assembly v-rew showlng the shown in Fig. 4 and it willbe noted that'the method by which the fin tubing is made. rollers 6 bendthe stock so that the stock has Fig. 2 is an enlarged detail showing howone leg portion 7 and another leg portion 8. the fin stock is treatedprior to being wound The bend, as shown, is one. of although upon thetube.. the anglemay be other than '90 as desired. Fig. -3 is a sectionalviewtaken through a For the purpose of convenience the portion rollermechanism which may be employed for pressing the fin stock tightly.against the tube, zontal port'no 0 'Fig. 4 is an enlarged section takenon line 4-4of Fig.2. to limit the angle to- 90. The stock thus Fig. 5 isa section on line 5-5 of Fig. 1 bout is drawn througha guide die 10posishowing one arrangement of the rollers which press-the fin stockagainst the tube, such rollthe stock is to be wound upon the tube. ershaving been shown in section in Fig; 3.

Fig. 6 is a sectional view on line 6-6 of metal oftheupright portionmust either be Fig. 3 showing the'completed tube. drawn or stretched toprovide for the varybut I haveshown inFig. 1 the In winding the stockupon the tube, the

8 will hereinafter be referred to as the horitioned immediately adjacentthe pointwhere A tube to which the fin stockis to be aping diametersbetween the outside. of the uplied is referenced 1. This tube isdisposed right portion and the inner-edge thereof, or

10 etween a air of rollers2and3which are roit may be crimped orcorrugated' I have tated and which engageopposite sides of the shown apair of, crimping rollers 11 and 12 tube and thus cause a rotation ofthe tube between which the upright portion of the around its centralaxis. These rollers are instock is engaged and corrugated as showndicative of any suitable mechanism for rotatat =13, in Fig. 6. Theroller-.11 mounted ing the tube. The direction of rotation ofupon asuitable shaft .14 whiclrF-is driven,

Fig. 3. The rollers are preferably disposed positively driven, a s'willat" an angle to each other, as clearly shown in the nature of the work.Fig. 1, and thus a line contact is bad with the opposite sides of thetube. The forward end. ers is, coordinated with the rotativelmoveof thetube advances into the fin applying ment' of the tube so that-the stripstock is mechanism. The advancement of the tube corrugated andwound u onthe tube. The

may be e ected by suitable driving rollers in tube with the strip stockt us wound thereon engagem nt with the tube (not shown), or advancesthrough a set of rollers 15. As no theadvancement of the tube may beeffected shown 1!; Fig. O'there are preferably three The Speedfofrotation of the crimpingrollo5 1... v these rollersis indicated bythe-arrows in and the. roller 12 mayueither; bean idler. or be.determined by tube it may the tube, as shown in Fig. 3. These rollersare preferably positively driven by means of a suitable gear wheel 16and an idler17. The speed of rotation of these rollers may becoordinated with that of the rotative movement of the tube so asto causethe advancement of the tube. 'If this should be done, the previouslyreferred to driving roller could-be omitted. On the other hand, theserollers can be held stationary and the ro-' tative movement of the tubethrough these worm rollers would cause the advancement of the tubeinasmuch as the spiral finengages in the grooves in the worm rollersmuch after the manner of a screw.

This applies the fin stock tothe tube. For the purpose of securing thefin stock to the be then passed through a heating die to meltthe coatingof solder on the fin stock and cause the same to adhere to the tube.However, a second coating of solder may be apv lied tothis strip, andthis is shown-in the di'awings, inasmuch, as it is thought to bepreferre For this purpose an acid may be sprayed overithe finned tube bya suitable nozzle 20, whereupon the tube advances throu h a solderlifting device 21. This solder. lifting device may be of any one ofthewell known constructlons for lifting molten solder from the' pot 22and pouring the molten solder over the tube. The solderj is keptmolten'by suitable desirable, the tube may be first passed through asweating dieto melt the coating of the fin stock and the second co'atinmay be applied'on'the outside. However, t e sweat-' ing operation may beomitted inasmuch as the heat-present in the solder bath 21 may besufiicient to melt the coating of solder on the finstock thussimultaneously applying solder bath and melting the coating of coolingwater'bathi26.

arm be utilized for Preferably, relatively long will be insertedinto thefin'applying msm, and if it is desirable to have the finished solder onthe fin stock.

Following this ste excess solder may be blown 05 by air sup led to asuitable nozzle 25 and directed against thetube. The tube may then becooled by through a ollowmg this, an-

other set of rollers insuring perfect formation of the completed tube.These rollers may be much the'sa'me as the set of rollers 15." y 1,

lengths of tube mechafin tubing in short lengths,'the tube may be cutoff in such proper short lengths as-it advances through the rollers 27This may be ting relation. burners 23. If.

accomplished by an automatic or hand out ofi device not shown.

Inasmuch as separate lengths of preformed tube are used, theproblemarises as to how to originally secure the fin stock to the tube when itfirst enters the fin applying mechanism. The preferred manner of doingthis is that of providing the crimping rollers 11 and 12 so as to givesuflicient curl to the stock to cause the stock to curl tightly aroundthe tube. In other words, the curl given to the stock by the crimpingrollers can be made so that the interior diameter of this curl isnormally slightly less than the outside diameter of the tubing. Thus thefin stock will tightly grip the tube under a slight spring pressure.This is sufficient to hold the tube and the fin stock in proper relationas it advances and until they are secured together by the solder. Afterthe first lengthv of tube has been started, a second length, and allfollowing lengths, may be starte by merely causing the forward end ofthe following lengths to abut directly against the rear end of the tubejust preceding, so that the fin stock wound continuously and covers thebreak between the two tubes.

After the fin stock is applied, the tubes canbe separated by cuttingthrough the fin stock at the abutting ends of two lengths of tube.

On the other hand, a thimble device, can be used to grip a portion ofthe forward end of a length of tube and the first convolution of windthe cent convolutions are in substantially abut- In other words, theouter edge of the horizontal portion in each convolution lies against orvery close to the point of juncture of the horizontal portionand theupright adjacent convolution.

portion in the next 'When the solder or other sealing metal is applieda' secure connectionsis made between the convolutions. Thus, there is aspiral reinforcing band covering all parts of the preformed tube. Thisadds strength to the tube and'permits' the use of tube made fromrelativelylight stock. 3

I claim: Y The method of m kin finnedtubing which consists in moving atue longitudinally, rotatingthe tube while it is so moving, drawing stri'ock from a supply, bending this strip stoc so that it is angular incross section to provide an upright and a horizontal portion, crim ingor corrugating the upright portion, winding this stock on the tube withthe upright portion forming-a continuous spiral fin on the tube directlyengaging the body of the tube to form a spiraLban'd on the tube.

' n testimony whereof I aflix my signature. HARRY W. BUNDY.

and with the horizontal portion

